I've blogged previously about Rails model extensions: how to use modules to break up complex models, or to share code between models.

So far I've been using the standard Ruby include to include the modules in the models, and the self.included hook to add class-level code.

This is not too elegant, so I came up with a plugin to make it more palatable.

See the github repository for the code and more details:

http://github.com/henrik/augmentations